Methods for preparing ruthenium and osmium compounds and films

ABSTRACT

The present invention provides methods for the preparation of compounds of the formula (Formula I):
 
L y M(CO) z 
 
wherein M is Ru or Os, each L is independently a neutral ligand, y=1-4, and z=1-5. These methods involve the reaction of Ru 3 (CO) 12  or Os 3 (CO) 12  with a neutral ligand in a solvent system having a boiling point higher than that of benzene at atmospheric pressure.

The present application is a continuation patent application of Ser. No.09/650,231, filed on Aug. 29, 2000, as U.S. Pat. No. 6,576,718, which isa continuation of patent application Ser. No. 09/372,427, filed on Aug.11, 1999, issued as U.S. Pat. No. 6,114,557, which is a continuation ofpatent application Ser. No. 09/141,431, filed Aug. 27, 1998, issued asU.S. Pat. No. 5,962,716, all of which are incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to the preparation of ruthenium and osmiumcompounds, which are particularly useful as chemical vapor depositionprecursors.

BACKGROUND OF THE INVENTION

Films of metals and metal oxides, particularly ruthenium and osmiumfilms and oxides thereof, are becoming important for a variety ofelectronic and electrochemical applications. For example, high qualityRuO₂ thin films deposited on silicon wafers have recently gainedinterest for use in ferroelectric memories. Ruthenium and osmium filmsare generally unreactive to silicon and metal oxides, resistant todiffusion of oxygen and silicon, and are good conductors. Oxides ofthese metals also possess these properties, although perhaps to adifferent extent.

Thus, films of ruthenium and osmium and oxides thereof have suitableproperties for a variety of uses in integrated circuits. For example,they can be used in integrated circuits for electrical contacts. Theyare particularly suitable for use as barrier layers between thedielectric material and the silicon substrate in memory devices, such asferroelectric memories. Furthermore, they may even be suitable as theplate (i.e., electrode) itself in capacitors.

There are a wide variety of ruthenium and osmium compounds that can beused as precursors for the preparation of such films. Many areparticularly well suited for use in chemical vapor depositiontechniques. See, for example, U.S. Pat. No. 5,372,849 (McCormick etal.), which discloses the use of ruthenium and osmium compoundscontaining carbonyl ligands and other ligands. Typically, such compoundscan be prepared by the thermal or photolytic reaction of Ru₃(CO)₁₂ orOs₃(CO)₁₂ with a neutral two electron donor ligand in benzene. See, forexample, Johnson et al., Nature, 901-902 (1967), and Cowles et al.,Chem. Commun., 392 (1969). Although such reactions provide good yields(e.g., 80-90%), they require generally long reaction times (e.g., 4days). Thus, there is a continuing need for methods for the preparationof such ruthenium and osmium compounds in high yields with shorterreaction times.

SUMMARY OF THE INVENTION

The present invention provides methods for the preparation of compoundsof the formula (Formula I):L_(y)M(CO)_(z)wherein M is Ru or Os, each L is indepedently a neutral ligand, y=1-4,and z=1-5. These methods involve the reaction of Ru₃(CO)₁₂ or Os₃(CO)₁₂with a neutral ligand in a solvent system having a boiling point higherthan that of benzene at atmospheric pressure. The solvent system caninclude one solvent, such as toluene, xylene, substituted benzene,heptane, octane, nonane, or an azeotropic mixture. The azeotropicmixture can contain one or more solvents having a boiling point atatmospheric pressure higher than that of benzene.

Using methods of the present invention, the product yields arepreferably higher than conventional methods, and the reaction times areshorter than conventional methods. Preferably, using the methods of thepresent invention, a complex of Formula I is prepared in greater thanabout 90% yield, more preferably, in greater than about 95% yield, andmost preferably, in greater than about 99% yield. Preferably, using themethods of the present invention, a complex of Formula I is prepared inno greater than about 36 hours, and more preferably, in no greater thanabout 24 hours.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides methods for the preparation of compoundsof the formula (Formula I):L_(y)M(CO)_(z)wherein M is Ru or Os, each L is independently a neutral ligand, y=1-4(preferably, 1-3, and more preferably, 1), and z=1-5 (preferably, 1-3,and more preferably, 3). These complexes are neutral complexes and maybe liquids or solids at room temperature. Typically, they are liquids.If they are solids, they are sufficiently soluble in an organic solventto allow for vaporization, they can be flash vaporized or sublimed fromthe solid state, or they have melting temperatures below theirdecomposition temperatures. Thus, such complexes described herein aresuitable for use in chemical vapor deposition (CVD) techniques, such asflash vaporization techniques, bubbler techniques, and/or microdroplettechniques. Preferred embodiments of the complexes described herein areparticularly suitable for low temperature CVD techniques.

These methods involve the reaction of Ru₃(CO)₁₂ or Os₃(CO)₁₂ (referredto herein as “trimer”) with a neutral ligand in a solvent system havinga boiling point higher than that of benzene at atmospheric pressure. Thereaction can occur thermally or photolytically. The solvent systemhaving a boiling point higher than that of benzene at atmosphericpressure can include one solvent or a mixture of solvents that may forman azeotrope. Preferably, the solvent system includes one or moresolvents that are less hazardous to an individual than benzene.

The solvents that are suitable for this application can be one or moreof the following: saturated or unsaturated hydrocarbons (preferably,C₆-C₂₀, cyclic, branched, or linear), aromatic hydrocarbons (preferably,C₆-C₂₀), halogenated hydrocarbons, silylated hydrocarbons such asalkylsilanes, alkylsilicates, ethers, polyethers, thioethers, esters,lactones, amides, amines (aliphatic or aromatic, primary, secondary, ortertiary), polyamines, nitrites, cyanates, isocyanates, thiocyanates,silicone oils, aldehydes, ketones, diketones, carboxylic acids,alcohols, thiols, or compounds containing combinations of any of theabove, or mixtures of one or more of the above.

The solvent system preferably includes, for example, toluene, xylene,substituted benzene (e.g., ethylbenzene), heptane, octane, nonane, ormixtures, particularly azeotropic mixtures thereof. The mixtures cancontain one or more solvents having a boiling point higher than that ofbenzene at atmospheric pressure.

The ligands L that are suitable for use in the preparation of compoundsof Formula I include neutral ligands. Examples of such ligands includephosphines (R₃P), phosphites ((RO)₃P), amines (R₃N), arsines (R₃As),stibenes (R₃Sb), ethers (R₂O), sulfides (R₂S), nitriles (RCN),isonitriles (RNC), thiocarbonyls (CS), monoalkenes (linear, branched, orcyclic), dienes (linear, branched, or cyclic), trienes (linear,branched, or cyclic), bicyclic alkenes, bicyclic dienes, bicyclictrienes, tricyclic alkenes, tricyclic dienes, tricyclic trienes, andalkynes. Although the structures for each of the unsaturated ligands(monoalkenes, dienes, trienes, alkynes, etc.) are not shown, they wouldalso include R groups attached to the main carbon chain. The R groupscan be hydrogen, a halide (particularly fluorine), or an organic group,which may be substituted or unsubstituted. The organic R groupspreferably include about 1 to about 8 carbon atoms, and more preferably,about 1 to about 2 carbon atoms. The unsaturated ligands preferablyinclude about 4 to about 8 carbon atoms, and more preferably, about 6 toabout 8 carbon atoms. Preferably, the neutral ligands are selected fromthe group of linear, branched, or cyclic dienes, bicyclic dienes,tricyclic dienes, and combinations thereof.

As used herein, the term “organic group” means a hydrocarbon group (withoptional elements other than carbon and hydrogen, such as oxygen,nitrogen, sulfur, and silicon) that is classified as an aliphatic group,cyclic group, or combination of aliphatic and cyclic groups (e.g.,alkaryl and aralkyl groups). In the context of the present invention,the organic groups are those that do not interfere with the formation ofcompounds of Formula I. The term “aliphatic group” means a saturated orunsaturated linear or branched hydrocarbon group. This term is used toencompass alkyl, alkenyl, and alkynyl groups, for example. The term“alkyl group” means a saturated linear or branched hydrocarbon groupincluding, for example, methyl, ethyl, isopropyl, t-butyl, heptyl,dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term “alkenylgroup” means an unsaturated, linear or branched hydrocarbon group withone or more carbon-carbon double bonds, such as a vinyl group. The term“alkynyl group” means an unsaturated, linear or branched hydrocarbongroup with one or more carbon-carbon triple bonds. The term “cyclicgroup” means a closed ring hydrocarbon group that is classified as analicyclic group, aromatic group, or heterocyclic group. The term“alicyclic group” means a cyclic hydrocarbon group having propertiesresembling those of aliphatic groups. The term “aromatic group” or “arylgroup” means a mono- or polynuclear aromatic hydrocarbon group. The term“heterocyclic group” means a closed ring hydrocarbon in which one ormore of the atoms in the ring is an element other than carbon (e.g.,nitrogen, oxygen, sulfur, etc.).

Substitution is anticipated on the organic groups of the complexes ofthe present invention. As a means of simplifying the discussion andrecitation of certain terminology used throughout this application, theterms “group” and “moiety” are used to differentiate between chemicalspecies that allow for substitution or that may be substituted and thosethat do not allow or may not be so substituted. Thus, when the term“group” is used to describe a chemical substituent, the describedchemical material includes the unsubstituted group and that group withO, N, Si, or S atoms, for example, in the chain (as in an alkoxy group)as well as carbonyl groups or other conventional substitution. Where theterm “moiety” is used to describe a chemical compound or substituent,only an unsubstituted chemical material is intended to be included. Forexample, the phrase “alkyl group” is intended to include not only pureopen chain saturated hydrocarbon alkyl substituents, such as methyl,ethyl, propyl, t-butyl, and the like, but also alkyl substituentsbearing further substituents known in the art, such as hydroxy, alkoxy,alkylsulfonyl, halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus,“alkyl group” includes ether groups, haloalkyls, nitroalkyls,carboxyalkyls, hydroxyalkyls, sulfoalkyls, etc. On the other hand, thephrase “alkyl moiety” is limited to the inclusion of only pure openchain saturated hydrocarbon alkyl substituents, such as methyl, ethyl,propyl, t-butyl, and the like.

Complexes of Formula I are disclosed, for example in U.S. Pat. No.5,372,849 (McCormick et al.) and U.S. Pat. No. 6,063,705 (Vaartstra). Apreferred class of complexes formed by the methods of the presentinvention include (cyclohexadienyl)Ru(CO)₃ and(cycloheptadienyl)Ru(CO)₃. These complexes are particularly advantageousbecause they are volatile liquids.

The methods of the present invention include using the ligand L in anexcess amount (e.g., up to about a 20-fold excess, and preferably, about3-fold to about 10-fold excess) relative to the ruthenium or osmiumtrimer, optionally in the presence of CO, at a temperature at which thesolvent system refluxes. The total amount of ligand L can be added tothe trimer initially, or it can be added in portions throughout thereaction. Alternatively, the total amount of trimer or portions thereofmay be added to ligand L. The reaction can be carried out in air,however, it is preferably carried out in an inert atmosphere (e.g.,nitrogen or argon) using refluxing apparatus.

Significantly, using a solvent or mixture of solvents having a boilingpoint greater than that of benzene at atmospheric pressure produces acomplex of Formula I in relatively high yields (preferably, greater thanabout 90% yield, more preferably, greater than about 95%, and mostpreferably, greater than about 99%) in a relatively short period of time(preferably, in no greater than about 36 hours, and more preferably, inno greater than about 24 hours). Compared to the same reaction inbenzene, the present invention can provide significantly shorterreaction times and higher yields.

The product can be isolated from the reaction mixture in a variety ofways. Typically, it is isolated by removing the solvent(s) and unreactedligand in vacuo, with optional heating of the reaction mixture.Significantly, once removed from the product, the solvent(s) andunreacted ligand can be reused by adding trimer in the desired amount.

The following examples are offered to further illustrate the variousspecific and preferred embodiments and techniques. It should beunderstood, however, that many variations and modifications may be madewhile remaining within the scope of the present invention.

EXAMPLES

All experiments were carried out under argon using standard inert gastechniques. FTIR spectra were run on a Nicolet Magna-IR 550Spectrometer. Mass spectra were collected on a Varian Saturn IIinstrument. NMR spectra were obtained at Spectral Data Services,Champaign, Ill.

Preparation of Tricarbonyl(1,3-cyclohexadiene)ruthenium

Under an atmosphere of dry argon, toluene (30 mL) and 1,3-cyclohexadiene(22.3 mL, 18.75 g, 234 mmol) were added to triruthenium dodecacarbonyl(10 g, 15.6 mmol). The red colored reaction mixture was heated toreflux. After 24 hours, the solution had a red/yellow color and thereflux was stopped. The solvent and the unreacted ligand were removed invacuo. Vacuum distillation of the remaining solution yieldedtricarbonyl(1,3-cyclohexadiene)ruthenium (12 g, 45.2 mmol) as a lightyellow liquid that was collected at approximately 35° C. and 50 mTorr.Yield: 96.6%. FTIR (in Nujol): 2061, 2986, 1953, 1181, 585, 558, 529,504 cm⁻¹. ¹H NMR (in C₆D₆): δ 4.8 dd, 2.8 m, 1.4 m. ¹³C[¹H] NMR (inC₆D₆): δ 199 s, 87 d, 56 d, 25 t. Mass spec: m/e 236, 208, 153, 130,102, 78, 63, 39.

For comparison purposes, see U.S. Pat. No. 6,063,705 (Vaartstra).Therein, the above complex was synthesized in refluxing benzene,producing a yield of about 70% and requiring a reaction time of about 5days.

Preparation of Tricarbonyl(1,3-cycloheptadiene)ruthenium

Under an atmosphere of dry argon, toluene (20 mL) and1,3-cycloheptadiene (2.0 mL, 1.74 g, 18.4 mmol) are added totriruthenium dodecacarbonyl (1.0 g, 1.56 mmol). The red colored reactionmixture is heated to reflux. After 24 hours, the solution has ared/yellow color and the reflux was stopped. The solvent and theunreacted ligand were removed in vacuo. Vacuum distillation of theremaining solution yields tricarbonyl(1,3-cycloheptadiene)ruthenium as alight yellow liquid that is collected at approximately 50° C. and 70mTorr. FTIR (in Nujol): 3038, 2981, 2060, 1995, 1970, 1055, 580, 560,525 cm⁻¹. ¹H NMR (in C₆D₆): δ 4.8 dd, 2.7 m, 1.65 m, 1.15 m. ¹³C[¹H] NMR(in C₆D₆): δ 90 d, 54 d, 28 t., 27.5 t.

All patents, patent applications, and publications are hereinincorporated by reference in their entirety, as if each wereindividually incorporated. The foregoing detailed description andexamples have been given for clarity of understanding only. Nounnecessary limitations are to be understood therefrom. The invention isnot limited to the exact details shown and described, for variationsobvious to one skilled in the art will be included within the inventiondefined by the claims.

1. A method of applying a metal-containing film on a surface of asubstrate comprising: preparing a compound of Formula I:L_(y)M(CO)_(z) wherein M is Ru or Os, each L is independently a neutralligand, y=1-4, and z=1-5, the method comprising reacting Ru₃(CO)₁₂ orOs₃(CO)₁₂ with a neutral ligand in a solvent system having a boilingpoint higher than that of benzene at atmospheric pressure and whereinthe solvent system comprises two or more solvents; and employing achemical vapor deposition technique to decompose the compound of FormulaI.
 2. The method of claim 1 wherein the solvent system comprises asolvent selected from the group of saturated or unsaturatedhydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, silylatedhydrocarbons, ethers, polyethers, thioethers, esters, lactones, amides,amines, polyamines, nitriles, cyanates, isocyanates, thiocyanates,silicone oils, aldehydes, ketones, diketones, carboxylic acids,alcohols, thiols, and mixtures of one or more of the above.
 3. Themethod of claim 1 wherein each L is independently selected from thegroup of phosphines, phosphites, amines, arsines, stibenes, ethers,sulfides, alkylidenes, nitriles, isonitriles, thiocarbonyls, linear,branched, or cyclic monoalkenes, linear, branched, or cyclic dienes,linear, branched, or cyclic trienes, bicyclic alkenes, bicyclic dienes,bicyclic trienes, tricyclic alkenes, tricyclic dienes, tricyclictrienes, and alkynes.
 4. The method of claim 1 wherein L is selectedfrom the group of linear, branched, or cyclic dienes, bicyclic dienes,tricyclic dienes, and combinations thereof.
 5. The method of claim 1wherein reacting further comprises reacting in an inert atmosphere. 6.The method of claim 1 wherein the neutral ligand is present in an amountof up to about a 20-fold excess relative to Ru₃(CO)₁₂ or Os₃(CO)₁₂. 7.The method of claim 6 wherein the neutral ligand is present in an amountof about a 3-fold excess to about a 10-fold excess relative to Ru₃(CO)₁₂or Os₃(CO)₁₂.
 8. The method of claim 1 wherein reacting furthercomprises reacting in the presence of CO.
 9. A method of applying ametal-containing film on a surface of a substrate comprising: preparinga compound of Formula I:L_(y)M(CO)_(z) wherein M is Ru or Os, each L is independently a neutralligand, y=1-4, and z=1-5, the method comprising reacting Ru₃(CO)₁₂ orOs₃(CO)₁₂ in the presence of CO with a neutral ligand in a solventsystem having a boiling point higher than that of benzene at atmosphericpressure; and employing a chemical vapor deposition technique todecompose the compound of Formula I.
 10. The method of claim 9 whereinreacting further comprises reacting to provide a reaction mixture andvacuum distilling the reaction mixture.
 11. The method of claim 9wherein the neutral ligand is present in an amount of at least about a3-fold excess relative to Ru₃(CO)₁₂ or Os₃(CO)₁₂.
 12. A method ofapplying a metal-containing film on a surface of a substrate comprising:preparing a compound of Formula I:L_(y)M(CO)_(z) wherein M is Ru or Os, each L is independently a neutralligand, y=1-4, and z=1-5, the method comprising reacting Ru₃(CO)₁₂ orOs₃(CO)₁₂ with a neutral ligand in a solvent system having a boilingpoint higher than that of benzene at atmospheric pressure, wherein acomplex of Formula I is prepared in an amount of greater than about 90%;and employing a chemical vapor deposition technique to decompose thecompound of Formula I.
 13. The method of claim 12 wherein the solventsystem comprises at least one solvent selected from the group oftoluene, xylene, substituted benzene, heptane, octane, nonane, andcombinations thereof.
 14. The method of claim 12 wherein a complex ofFormula I is prepared in an amount of greater than about 90% in nogreater than about 36 hours.
 15. The method of claim 12 wherein acomplex of Formula I is prepared in an amount of greater than about 95%.16. The method of claim 15 wherein a complex of Formula I is prepared inan amount of greater than about 95% in no greater than about 36 hours.17. The method of claim 16 wherein a complex of Formula I is prepared inan amount of greater than about 95% in no greater than about 24 hours.18. The method of claim 12 wherein reacting further comprises reactingto provide a reaction mixture and vacuum distilling the reactionmixture.
 19. The method of claim 12 wherein a complex of Formula I isprepared in an amount of greater than about 99%.
 20. The method of claim19 wherein the solvent system comprises only one solvent.
 21. The methodof claim 19 wherein the solvent system comprises two or more solvents.22. The method of claim 19 wherein a complex of Formula I is prepared inan amount of greater than about 99% in no greater than about 24 hours.23. A method of applying a metal-containing film on a surface of asubstrate comprising: preparing a compound of Formula I:L_(y)M(CO)_(z) wherein M is Ru or Os, each L is independently a neutralligand, y=1-4, and z=1-5, the method comprising reacting Ru₃(CO)₁₂ orOs₃(CO)₁₂ in an inert atmosphere with a neutral ligand in a solventsystem having a boiling point higher than that of benzene at atmosphericpressure, and isolating the compound of Formula I by removing thesolvent system and unreacted ligand in vacuo; and employing a chemicalvapor deposition technique to decompose the compound of Formula I. 24.The method of claim 23 wherein the inert atmosphere is selected from thegroup consisting of nitrogen and argon.
 25. A method of applying ametal-containing film on a surface of a substrate comprising: preparinga compound of Formula I:L_(y)M(CO)_(z) wherein M is Ru or Os, each L is independently a neutralligand, y=1-4, and z=1-5, the method comprising: reacting Ru₃(CO)₁₂ orOs₃(CO)₁₂ in an inert atmosphere with a neutral ligand in a solventsystem having a boiling point higher than that of benzene at atmosphericpressure to provide a reaction mixture; and vacuum distilling thereaction mixture; and employing a chemical vapor deposition technique todecompose the compound of Formula I.
 26. The method of claim 25 whereinthe vacuum distilling is carried out at a pressure less than about 70mTorr.
 27. The method of claim 25 wherein the reaction mixture isheated.
 28. The method of claim 27 wherein the reaction mixture isheated to at least about 35° C.
 29. The method of claim 28 wherein thevacuum distilling is carried out at a pressure less than about 70 mTorr.30. A method of applying a metal-containing film on a surface of asubstrate comprising: preparing a compound of Formula I:L_(y)M(CO)_(z) wherein M is Ru or Os, each L is independently a neutralligand, y=1-4, and z=1-5, the method comprising reacting Ru₃(CO)₁₂ orOs₃(CO)₁₂ in an inert atmosphere with a neutral ligand in a solventsystem having a boiling point higher than that of benzene at atmosphericpressure; wherein the neutral ligand is present in an amount of up toabout a 20-fold excess relative to Ru₃(CO)₁₂ or Os₃(CO)₁₂; and employinga chemical vapor deposition technique to decompose the compound ofFormula I.